diff --git a/src/test/java/org/apache/datasketches/kll/KllCrossLanguageTest.java b/src/test/java/org/apache/datasketches/kll/KllCrossLanguageTest.java
index 45fb4d8c9..f1b578229 100644
--- a/src/test/java/org/apache/datasketches/kll/KllCrossLanguageTest.java
+++ b/src/test/java/org/apache/datasketches/kll/KllCrossLanguageTest.java
@@ -44,6 +44,7 @@
 import org.apache.datasketches.quantilescommon.QuantilesDoublesSketchIteratorAPI;
 import org.apache.datasketches.quantilescommon.QuantilesFloatsSketchIterator;
 import org.apache.datasketches.quantilescommon.QuantilesGenericSketchIteratorAPI;
+import org.apache.datasketches.quantilescommon.QuantilesLongsSketchIterator;
 import org.testng.annotations.Test;
 
 /**
@@ -209,4 +210,28 @@ public int compare(final String s1, final String s2) {
     }
   }
 
+  @Test(groups = {CHECK_CPP_FILES})
+  public void kllLong() throws IOException {
+    final int[] nArr = {0, 10, 100, 1000, 10000, 100000, 1000000};
+    for (final int n: nArr) {
+      final byte[] bytes = Files.readAllBytes(cppPath.resolve("kll_long_n" + n + "_cpp.sk"));
+      final KllLongsSketch sketch = KllLongsSketch.heapify(MemorySegment.ofArray(bytes));
+      assertEquals(sketch.getK(), 200);
+      assertTrue(n == 0 ? sketch.isEmpty() : !sketch.isEmpty());
+      assertTrue(n > 100 ? sketch.isEstimationMode() : !sketch.isEstimationMode());
+      assertEquals(sketch.getN(), n);
+      if (n > 0) {
+        assertEquals(sketch.getMinItem(), 1);
+        assertEquals(sketch.getMaxItem(), n);
+        long weight = 0;
+        final QuantilesLongsSketchIterator it = sketch.iterator();
+        while (it.next()) {
+          assertTrue(it.getQuantile() >= sketch.getMinItem());
+          assertTrue(it.getQuantile() <= sketch.getMaxItem());
+          weight += it.getWeight();
+        }
+        assertEquals(weight, n);
+      }
+    }
+  }
 }